Methods and devices for transcarotid access

ABSTRACT

A micropuncture kit for direct access of a surgically exposed vessel using direct visual guidance includes a micropuncture access needle having a proximal hub coupled to an elongate shaft defining an inner lumen and a visible depth indicator positioned on the elongate shaft a distance away from a distal tip of the elongate shaft. The kit includes an access guidewire sized to be received through the inner lumen of the micropuncture access needle and a microaccess cannula having an elongate body defining an inner lumen and a plurality of visible depth indicators formed on the elongate body. The guidewire includes a distal tip and at least one visible depth indicator positioned on the access guidewire a distance away from the distal tip of the guidewire. Each of the plurality of visible depth indicators identifies a distance from a distal tip of the cannula. Related systems, devices and methods are provided.

REFERENCE TO PRIORITY DOCUMENT

This application is continuation-in-part of U.S. patent application Ser.No. 15/606,381, filed May 26, 2017, which is a continuation of U.S.patent application Ser. No. 15/210,770 entitled “METHODS AND DEVICES FORTRANSCAROTID ACCESS” filed Jul. 14, 2016, issuing on May 30, 2017 asU.S. Pat. No. 9,662,480, which is a continuation of U.S. patentapplication Ser. No. 15/005,770 entitled “METHODS AND DEVICES FORTRANSCAROTID ACCESS” filed Jan. 25, 2016, now U.S. Pat. No. 9,399,118,which is a continuation of U.S. patent application Ser. No. 14/575,199entitled “METHODS AND DEVICES FOR TRANSCAROTID ACCESS” filed Dec. 18,2014, now U.S. Pat. No. 9,126,018, which is a continuation of U.S.patent application Ser. No. 14/537,316 entitled “METHODS AND DEVICES FORTRANSCAROTID ACCESS” filed Nov. 10, 2014, now U.S. Pat. No. 9,241,699,which claims the benefit of priority to U.S. Provisional ApplicationSer. No. 62/046,112, entitled “METHODS AND DEVICES FOR TRANSCAROTIDACCESS” filed on Sep. 4, 2014, and U.S. Provisional Application Ser. No.62/075,169, entitled “METHODS AND DEVICES FOR TRANSCAROTID ACCESS” filedon Nov. 4, 2014. Priority of the aforementioned filing dates is claimedand the patent applications are incorporated herein by reference intheir entirety.

BACKGROUND

The present disclosure relates generally to medical methods, systems,and devices for performing endovascular interventions. Moreparticularly, the present disclosure relates to methods and systems foraccess directly into the carotid artery to perform interventionalprocedures in the treatment of vascular disease and other diseasesassociated with the vasculature.

Interventional procedures are performed to treat vascular disease, forexample stenosis, occlusions, aneurysms, or fistulae. Interventionalprocedures are also used to perform procedures on organs or tissuetargets that are accessible via blood vessels, for example denervationor ablation of tissue to intervene in nerve conduction, embolization ofvessels to restrict blood flow to tumors or other tissue, and deliveryof drugs, contrast, or other agents to intra or extravascular targetsfor therapeutic or diagnostic purposes. Interventional procedures aretypically divided into coronary, neurovascular, and peripheral vascularcategories. Most procedures are performed in the arterial system via anarterial access site.

Methods for gaining arterial access to perform these procedures arewell-established, and fall into two broad categories: percutaneousaccess and surgical cut-down. The majority of interventional proceduresutilize a percutaneous access. For this access method, a needle punctureis made from the skin, through the subcutaneous tissue and muscle layersto the vessel wall, and into the vessel itself. Vascular ultrasound isoften used to image the vessel and surrounding structures, andfacilitate accurate insertion of the needle into the vessel. Dependingon the size of the artery and of the access device, the method willvary, for example a Seldinger technique or modified Seldinger techniqueconsists of placing a sheath guide wire through the needle into thevessel. Typically the sheath guide wire is 0.035″ or 0.038″. In someinstances, a micro-puncture or micro access technique is used wherebythe vessel is initially accessed by a small gauge needle, andsuccessively dilated up by a 4F micropuncture cannula through which thesheath guidewire is placed. Once the guidewire is placed, an accesssheath and sheath dilator are inserted over the guide wire into theartery. In other instances, for example if a radial artery is being usedas an access site, a smaller sheath guidewire is used through theinitial needle puncture, for example a 0.018″ guidewire. The dilator ofa radial access sheath is designed to accommodate this smaller sizeguidewire, so that the access sheath and dilator can be inserted overthe 0.018″ wire into the artery.

In a surgical cut-down, a skin incision is made and tissue is dissectedaway to the level of the target artery. This method is often used if theprocedure requires a large access device, if there is risk to the vesselwith a percutaneous access, and/or if there is possibility of unreliableclosure at the access site at the conclusion of the procedure. Dependingon the size of the artery and of the access device, an incision is madeinto the wall of the vessel with a blade, or the vessel wall ispunctured directly by an access needle, through which a sheath guidewire is placed. The micropuncture technique may also be used to place asheath guide wire. As above, the access sheath and sheath dilator areinserted into the artery over the sheath guide wire. Once the accesssheath is placed, the dilator and sheath guide wire are removed. Devicescan now be introduced via the access sheath into the artery and advancedusing standard interventional techniques and fluoroscopy to the targetsite to perform the procedure.

Access to the target site is accomplished from an arterial access sitethat is easily entered from the skin. Usually this is the femoral arterywhich is both relatively large and relatively superficial, and easy toclose on completion of the procedure using either direct compression orone of a variety of vessel closure devices. For this reason,endovascular devices are specifically designed for this femoral accesssite. However, the femoral artery and its vicinity are sometimesdiseased, making it difficult or impossible to safely access orintroduce a device into the vasculature from this site. In addition, thetreatment target site may be quite some distance from the femoral accesspoint requiring devices to be quite lengthy and cumbersome. Further,reaching the target site from the femoral access point may involvetraversing tortuous and/or diseased arteries, which adds time and riskto the procedure. For these reasons, alternate access sites aresometimes employed. These include the radial, brachial and axillaryarteries. However, these access sites are not always ideal, as theyinvolve smaller arteries and may also include tortuous segments and somedistance between the access and target sites.

Some Exemplary Issues with Current Technology

In some instances, a desired access site is the carotid artery. Forexample, procedures to treat disease at the carotid artery bifurcationand internal carotid artery are quite close to this access site.Procedures in the intracranial and cerebral arteries are likewise muchcloser to this access site than the femoral artery. This artery is alsolarger than some of the alternate access arteries noted above. (Thecommon carotid artery is typically 6 to 10 mm in diameter, the radialartery is 2 to 3 mm in diameter.)

Because most access devices used in interventional procedure aredesigned for the femoral access, these devices are not ideal for thealternate carotid access sites, both in length and mechanicalproperties. This makes the procedure more cumbersome and in some casesmore risky if using devices designed for femoral access in a carotidaccess procedure. For example, in some procedures it is desirable tokeep the distal tip of the access sheath below or away from the carotidbifurcation, for example in procedures involving placing a stent at thecarotid bifurcation. For patients with a low bifurcation, a short neck,or a very deep carotid artery, the angle of entry of the sheath into theartery (relative to the longitudinal axis of the artery) is very acutewith respect to the longitudinal axis of the artery, i.e. moreperpendicular than parallel relative to the longitudinal axis of theartery. This acute angle increases the difficulty and risk in sheathinsertion and in insertion of devices through the sheath. In theseprocedures, there is also risk of the sheath dislodgement as only aminimal length of sheath can be inserted. In femoral or radial accesscases, the sheaths are typically inserted into the artery all the way tothe hub of the sheath, making sheath position very secure and parallelto the artery, so that the issues with steep insertion angle and sheathdislodgement do not occur in femoral or radial access sites.

In other procedures, it is desirable to position the sheath tip up toand possibly including the petrous portion of the internal carotidartery, for example in procedures requiring access to cerebral vessels.Conventional interventional sheaths and sheath dilators are not flexibleenough to be safely positioned at this site.

In addition, radiation exposure may be a problem for the hands of theoperators for procedures utilizing a transcarotid access site, if theworking areas are close to the access site.

SUMMARY

What is needed is a system of devices that optimize ease and safety ofarterial access directly into the common carotid artery. What is alsoneeded is a system of devices which minimize radiation exposure to theoperator. What are also needed are methods for safe and easy access intothe carotid artery to perform peripheral and neurovascularinterventional procedures.

Disclosed are methods and devices that enable safe, rapid and relativelyshort and straight transcarotid access to the arterial vasculature totreat coronary, peripheral and neurovascular disease states. The devicesand associated methods include transcarotid access devices, guidecatheters, catheters, and guide wires specifically to reach a targetanatomy via a transcarotid access site. Included in this disclosure arekits of various combinations of these devices to facilitate multipletypes of transcarotid interventional procedures.

In one aspect, there is disclosed a system of devices for accessing acarotid artery via a direct puncture of the carotid arterial wall,comprising a sheath guide wire, an arterial access sheath and a sheathdilator, wherein the arterial access sheath and sheath dilator are sizedand configured to be inserted in combination over the sheath guide wiredirectly into the common carotid artery, and wherein the sheath has aninternal lumen and a proximal port such that the lumen provides apassageway for an interventional device to be inserted via the proximalport into the carotid artery.

In another aspect, the system for accessing a carotid artery alsoincludes: an access needle, an access guide wire, and an access cannula,all sized and configured to insert a sheath guide wire through the wallof the carotid artery so that the arterial access sheath and dilator maybe placed into the carotid artery either percutaneously or via asurgical cut down.

In another aspect, there is disclosed a method for treatment ofcoronary, peripheral or neurovascular disease, comprising: forming apenetration in a wall of a carotid artery; positioning an arterialaccess sheath through the penetration into the artery; and treating atarget site using a treatment device.

In another aspect, there is disclosed an arterial access sheath forintroducing an interventional device into an artery. The arterial accesssheath includes an elongated body sized and shaped to be transcervicallyintroduced into a common carotid artery at an access location in theneck and an internal lumen in the elongated body having a proximalopening in a proximal region of the elongated body and a distal openingin a distal region of the elongated body. The internal lumen provides apassageway for introducing an interventional device into the commoncarotid artery when the elongated body is positioned in the commoncarotid artery. The elongated body has a proximal section and adistalmost section that is more flexible than the proximal section. Aratio of an entire length of the distalmost section to an overall lengthof the sheath body is one tenth to one half the overall length of thesheath body.

In an interrelated aspect, there is disclosed a micropuncture kit fordirect access into a lumen of a surgically exposed vessel using directvisual guidance. The kit includes a micropuncture access needle having aproximal hub coupled to an elongate shaft defining an inner lumen and avisible depth indicator positioned on the elongate shaft a distance awayfrom a distal tip of the elongate shaft. The kit includes an accessguidewire sized to be received through the inner lumen of themicropuncture access needle. The guidewire includes a distal tip and atleast one visible depth indicator positioned on the access guidewire adistance away from the distal tip of the guidewire. The kit includes amicroaccess cannula having an elongate body defining an inner lumen anda plurality of visible depth indicators formed on the elongate body,wherein each of the plurality of visible depth indicators identifies adistance from a distal tip of the cannula.

The access guidewire can include a distalmost flexible section includingthe distal tip of the guidewire, a transition section proximal to thedistalmost flexible section, and a stiffer core section extendingproximally from the transition section. The distalmost flexible sectioncan be between 1 cm and 2 cm, and the transition section can be between2 cm and 3 cm. The transition section and the core section can beconfigured to support the microaccess cannula inserted into the vessel.The guidewire can be in a range of 0.014″ to 0.018″ outer diameter andthe micropuncture needle can be in a range from 21 G to 24 G. The atleast one visible depth indicator positioned on the access guidewire canhave a proximal edge, a distal edge and a width extending between theproximal edge and the distal edge. The distance away from the distal tipof the guidewire can be measured from the distal tip to the distal edgeof the at least one visible depth indicator. Inserting the accessguidewire through the inner lumen of the elongate shaft until the distaledge is aligned with a back end of the proximal hub of the access needlecan extend the distal tip of the guidewire beyond the distal tip of theelongate shaft an extension length. Advancing the access guidewirethrough the inner lumen of the elongate shaft until the proximal edge isaligned with the back end of the proximal hub of the access needle canextend the distal tip of the guidewire beyond the distal tip of theelongate shaft the extension length plus the width of the at least onevisible depth indicator. The extension length can be 3 cm and the widthof the at least one visible depth indicator can be 2 cm. The visibledepth indicator of the access needle can be a chemical-etched marker, alaser-etched marker, or a pad printed marker. Each of the plurality ofvisible depth indicators can be formed by a number of marks. The numberof marks can identify a number of increments from the distal tip of thecannula. Each increment can be 10 mm and the number of marks can be atleast one mark. A first of the plurality of visible depth indicators onthe cannula can include one mark and the first visible depth indicatorcan be 10 mm away from the distal tip of the cannula. A second of theplurality of visible depth indicators on the cannula can be two marksand the second visible depth indicator can be 20 mm away from the distaltip of the cannula. A third of the plurality of visible depth indicatorson the cannula can be three marks and the third visible depth indicatorcan be 30 mm away from the distal tip of the cannula. A fourth of theplurality of visible depth indicators on the cannula can be four marksand the fourth visible depth indicator can be 40 mm away from the distaltip of the cannula. A fifth of the plurality of visible depth indicatorson the cannula can be 50 mm away from the distal tip of the cannula andcan be a solid band having a width that is greater than a width of onemark. The distance the visible depth indicator of the access needle isfrom the distal tip of the elongate shaft can be between 3 mm and 7 mm.The visible depth indicator of the access needle can be achemical-etched marker, a laser-etched marker, or a pad printed marker.

Other features and advantages should be apparent from the followingdescription of various embodiments, which illustrate, by way of example,the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a transcarotid initial access system.

FIG. 2 shows a transcarotid access sheath system.

FIG. 3 shows a component of the transcarotid access system being used toaccess a carotid artery for a carotid artery procedure.

FIG. 4 shows an access sheath of the transcarotid access system beingused to access an internal carotid artery for an intracranial orneurovascular procedure.

FIG. 5 shows an embodiment of an arterial access sheath.

FIGS. 6 and 7 show distal regions of an arterial access sheath.

FIGS. 8-11E show embodiments of an arterial access sheath.

FIG. 12 shows an embodiment of a dilator.

FIGS. 13 and 14 show enlarged views of the proximal region of thedilator.

FIGS. 15 and 16 show embodiments of a two part dilator.

FIG. 17 shows a distal region of a dilator having two guidewire lumens.

FIG. 18 shows a cross-sectional view of the distal region of FIG. 17.

FIG. 19A shows an implementation of a transcarotid initial accesssystem.

FIG. 19B shows a detail view of the access needle of FIG. 19A taken atcircle B-B.

FIG. 20A illustrates a distal end region of an implementation of anaccess guidewire.

FIGS. 20B-20C illustrate relative extension of the access guidewire ofFIG. 20A and the access needle of FIG. 19A.

FIG. 21A is an implementation of a microaccess cannula.

FIG. 21B is a detail view of the microaccess cannula taken at circle B-Bof FIG. 21A.

DETAILED DESCRIPTION

Disclosed are methods, systems, and devices for accessing and treatingthe vasculature via a transcarotid access point in the region of thecarotid artery.

FIG. 1 shows a first embodiment of a transcarotid initial access system100 of devices for establishing initial access to a carotid artery forthe purpose of enabling introduction of a guide wire into the carotidartery. The access to the carotid artery occurs at an access sitelocated in the neck of a patient such as in the region of the patient'scarotid artery. The devices of the transcarotid initial access system100 are particularly suited for directly accessing the carotid arterythrough the wall of the common carotid artery.

As shown in FIG. 1, the transcarotid initial access system 100 includesan access needle 120, access guidewire 140, and micropuncture cannula160. The access needle 120, access guidewire 140, and micropuncturecannula 160 are all adapted to be introduced via a carotid puncture intothe carotid artery as further described below. The carotid puncture maybe accomplished, for example, percutaneously or via a surgical cut down.Embodiments of the initial access system 100 may be adapted towards oneor the other method of puncture, as further described below.

Upon establishment of access to the carotid artery using the initialaccess system 100, an access sheath may be inserted into the carotidartery at the access site wherein the access sheath may be part of atranscarotid access sheath system. FIG. 2 shows a first embodiment of atranscarotid access sheath system 200 of devices for inserting an accesssheath into the carotid artery over a sheath guidewire. When insertedinto the carotid artery, the access sheath enables or allowsintroduction of at least one interventional device into the carotidartery via a lumen of the access sheath for the purpose of performing aninterventional procedure on a region of the vasculature. Thetranscarotid access sheath system 200 includes an access sheath 220, asheath dilator 260, and a sheath guidewire 300. The access sheath 220,sheath dilator 260 and sheath guidewire 300 are all adapted to beintroduced via a carotid puncture into the carotid artery as furtherdescribed below. The carotid puncture may be accomplished percutaneouslyor via a surgical cut down. Embodiments of the system 200 may be adaptedtowards one or the other method of puncture, as further described below.

In an embodiment, some or all of the components of transcarotid initialaccess system 100 and the transcarotid access sheath system 200 may becombined into one transcarotid access system kit such as by combiningthe components into a single, package, container or a collection ofcontainers that are bundled together.

FIG. 3 shows the access sheath 220 being used to access a common carotidartery 310 for a carotid stenting procedure. The access sheath 220 isinserted into the common carotid artery 310 via a surgical cut down 315.As described further below, the access sheath 220 has an internal lumenwith openings at proximal and distal tips or regions of the accesssheath 220. With a distal portion of the access sheath 220 in thecarotid artery and a proximal portion external to the patient, theinternal lumen provides a passageway to insert an interventional deviceinto the artery.

FIG. 4 shows an access sheath 200 of the transcarotid access systembeing used to access an internal carotid artery 405 for an intracranialor neurovascular procedure. The arterial access sheath 200 accesses thecommon carotid artery 310 via insertion through a transcervicalpuncture. Once inserted into the common carotid artery 310, the distaltip of the access sheath 220 is advanced into the internal carotidartery ICA 320 and upward (relative to the puncture in FIG. 4) towarddistal cervical or petrous ICA 405 or beyond.

FIGS. 3 and 4 both show the arterial access sheath 220 being advancedupward through the patient's neck toward the patient's brain. In anotherembodiment, the arterial access sheath 220 may be advanced downward(relative to access locations in FIGS. 3-4) toward the patient's heartsuch as toward the aorta for example. U.S. Pat. No. 8,545,552 entitled“Systems and Methods for Transcatheter Aortic Valve Treatment” (which isincorporated herein by reference) describes exemplary methods ofdirectly inserting an access sheath into the carotid artery andadvancing an interventional device toward the aorta and ultimatelytowards the aortic valve.

Arterial Access Sheath

With reference again to FIG. 2, an embodiment of a transcarotid arterialaccess sheath 220 includes an elongated sheath body 222 and a proximaladaptor 224 at a proximal end of the elongated sheath body 222 of theaccess sheath 220. The elongated sheath body 222 is the portion of thearterial access sheath 220 that is sized and shaped to be inserted intothe artery and wherein at least a portion of the elongated sheath bodyis actually inserted into the artery during a procedure. The proximaladaptor 224 includes a hemostasis valve 226 and an elongated flush line228 having an internal lumen that communicates with an internal lumen ofthe sheath body 222. The proximal adaptor 224 may have a larger diameteror cross-sectional dimension than the sheath body 222. The hemostasisvalve 226 communicates with the internal lumen of the sheath body 222 toallow introduction of devices therein while preventing or minimizingblood loss via the internal lumen during the procedure. In anembodiment, the hemostasis valve 226 is a static seal-type passivevalve. In an alternate embodiment of the arterial access sheath 220(shown in FIG. 5) the hemostasis valve 226 is an adjustable-openingvalve such as a Tuohy-Borst valve 227 or rotating hemostasis valve(RHV). Alternately, the access sheath 220 may terminate on the proximalend in a female Luer adaptor to which a separate hemostasis valvecomponent may be attached, either a passive seal valve, a Tuohy-Borstvalve or rotating hemostasis valve (RHV).

The elongated sheath body 222 of the arterial access sheath 220 has adiameter that is suitable or particularly optimized to provide arterialaccess to the carotid artery. In an embodiment, the elongated sheathbody 222 is in a size range from 5 to 9 French, or alternately in aninner diameter range from 0.072 inches to 0.126 inches. In anembodiment, the elongated sheath body 222 is a 6 or 7 French sheath. Inan embodiment where the sheath is also used for aspiration or reverseflow, or to introduce larger devices, the sheath is an 8 French sheath.

The elongated sheath body 222 of the arterial access sheath 220 has alength from the proximal adapter 224 to a distal tip of the elongatedsheath body 222 that is suitable for reaching treatment sites located inor toward the brain relative to an arterial access site in the commoncarotid artery CCA. For example, to access a carotid artery bifurcationor proximal internal carotid artery ICA from a CCA access site, theelongated sheath body 222 (i.e., the portion that can be inserted intothe artery) of the access sheath 220 may have a length in a range from 7to 15 cm. In an embodiment, the elongated sheath body 222 has a lengthin the range of 10-12 cm. For access to a same target site from afemoral access site, typical access sheaths must be between 80 and 110cm, or a guide catheter must be inserted through an arterial accesssheath and advanced to the target site. A guide catheter through anaccess sheath takes up luminal area and thus restricts the size ofdevices that may be introduced to the target site. Thus an access sheaththat allows interventional devices to reach a target site without aguide catheter has advantages over an access sheath that requires use ofa guide catheter to allow interventional devices to the target site.

Alternately, to position the distal tip of the elongated sheath body 222more distally relative to the access site, for example to perform anintracranial or neurovascular procedure from a CCA access site, theelongated sheath body 222 of the access sheath 220 may have a length inthe range from 10 cm to 30 cm, depending on the desired target positionof the sheath distal tip. For example, if the target position is thedistal CCA or proximal ICA, the elongated sheath body 222 may be in therange from 10 cm to 15 cm. If the desired target position is the mid todistal cervical, petrous, or cavernous segments of the ICA, theelongated sheath body 222 may be in the range from 15 to 30 cm.

Alternately, the arterial access sheath 220 is configured or adapted fortreatment sites or target locations located proximal to the arterialaccess site (i.e. towards the aorta) when the access site is in thecommon carotid artery. For example the treatment site may be theproximal region of the CCA, CCA ostium, ascending or descending aorta oraortic arch, aortic valve, coronary arteries, or other peripheralarteries. For these target locations, the appropriate length of theelongated sheath body 222 depends on the distance from the targetlocation to the access site. In this configuration, the elongated sheathbody 222 is placed through an arterial access site and directedinferiorly towards the aorta.

The access sheath 220 may also include a radiopaque tip marker 230. Inan example the radiopaque tip marker is a metal band, for exampleplatinum iridium alloy, embedded near the distal end of the sheath body222 of the access sheath 220. Alternately, the access sheath tipmaterial may be a separate radiopaque material, for example a bariumpolymer or tungsten polymer blend. The sheath tip itself is configuredsuch that when the access sheath 220 is assembled with the sheathdilator 260 to form a sheath assembly, the sheath assembly can beinserted smoothly over the sheath guide wire 300 through the arterialpuncture with minimal resistance. In an embodiment, the elongated sheathbody 222 of the access sheath 220 has a lubricious or hydrophiliccoating to reduce friction during insertion into the artery. In anembodiment, the distal coating is limited to the distalmost 0.5 to 3 cmof the elongated sheath body 222, so that it facilitates insertionwithout compromising security of the sheath in the puncture site or theability of the operator to firmly grasp the sheath during insertion. Inan alternate embodiment, the sheath has no coating.

With reference to FIG. 2, in an embodiment, the arterial access sheath220 has features to aid in securement of the sheath during theprocedure. For example the access sheath 220 may have a suture eyelet234 or one or more ribs 236 molded into or otherwise attached to theadaptor 224 (located at the proximal end of the elongated sheath body222) which would allow the operator to suture tie the sheath hub to thepatient.

For a sheath adapted to be inserted into the common carotid artery forthe purpose of access to the carotid bifurcation, the length of theelongated sheath body 222 can be in the range from 7 to 15 cm, usuallybeing from 10 cm to 12 cm. The inner diameter is typically in the rangefrom 5 Fr (1 Fr=0.33 mm), to 10 Fr, usually being 6 to 8 Fr. For asheath adapted to be inserted via the common carotid artery to the midor distal internal carotid artery for the purpose of access to theintracranial or cerebral vessels, the length of the elongated sheathbody 222 can be in the range from 10 to 30 cm, usually being from 15 cmto 25 cm. The inner diameter is typically in the range from 5 Fr (1Fr=0.33 mm), to 10 Fr, usually being 5 to 6 Fr.

Particularly when the sheath is being introduced through thetranscarotid approach, above the clavicle but below the carotidbifurcation, it is desirable that the elongated sheath body 222 beflexible while retaining hoop strength to resist kinking or buckling.This is especially important in procedures that have limited amount ofsheath insertion into the artery, and there is a steep angle ofinsertion as with a transcarotid access in a patient with a deep carotidartery and/or with a short neck. In these instances, there is a tendencyfor the sheath body tip to be directed towards the back wall of theartery due to the stiffness of the sheath. This causes a risk of injuryfrom insertion of the sheath body itself, or from devices being insertedthrough the sheath into the arteries, such as guide wires. Alternately,the distal region of the sheath body may be placed in a distal carotidartery which includes one or more bends, such as the petrous ICA. Thus,it is desirable to construct the sheath body 222 such that it can beflexed when inserted in the artery, while not kinking. In an embodiment,the sheath body 222 is circumferentially reinforced, such as bystainless steel or nitinol braid, helical ribbon, helical wire, cutstainless steel or nitinol hypotube, cut rigid polymer, or the like, andan inner liner so that the reinforcement structure is sandwiched betweenan outer jacket layer and the inner liner. The inner liner may be a lowfriction material such as PTFE. The outer jacket may be one or more of agroup of materials including Pebax, thermoplastic polyurethane, ornylon.

In an embodiment, the sheath body 222 may vary in flexibility over itslength. This change in flexibility may be achieved by various methods.For example, the outer jacket may change in durometer and/or material atvarious sections. Alternately, the reinforcement structure or thematerials may change over the length of the sheath body. In oneembodiment, there is a distalmost section of sheath body 222 which ismore flexible than the remainder of the sheath body. For example, theflexural stiffness of the distalmost section is one third to one tenththe flexural stiffness of the remainder of the sheath body 222. In anembodiment, the distalmost section has a flexural stiffness (E*I) in therange 50 to 300 N-mm² and the remaining portion of the sheath body 222has a flexural stiffness in the range 500 to 1500 N-mm², where E is theelastic modulus and I is the area moment of inertia of the device. For asheath configured for a CCA access site, the flexible, distal mostsection comprises a significant portion of the sheath body 222 which maybe expressed as a ratio. In an embodiment, the ratio of length of theflexible, distalmost section to the overall length of the sheath body222 is at least one tenth and at most one half the length of the entiresheath body 222.

In some instances, the arterial access sheath is configured to access acarotid artery bifurcation or proximal internal carotid artery ICA froma CCA access site. In this instance, an embodiment of the sheath body222 has a distalmost section 223 which is 3 to 4 cm and the overallsheath body 222 is 10 to 12 cm. In this embodiment, the ratio of lengthof the flexible, distalmost section to the overall length of the sheathbody 222 is about one forth to one half the overall length of the sheathbody 222. In another embodiment, there is a transition section 225between the distalmost flexible section and the proximal section 231,with one or more sections of varying flexibilities between thedistalmost section and the remainder of the sheath body. In thisembodiment, the distalmost section is 2 to 4 cm, the transition sectionis 1 to 2 cm and the overall sheath body 222 is 10 to 12 cm, orexpressed as a ratio, the distalmost flexible section and the transitionsection collectively form at least one fourth and at most one half theentire length of the sheath body.

In some instances, the sheath body 222 of the arterial access sheath isconfigured to be inserted more distally into the internal carotid arteryrelative to the arterial access location, and possibly into theintracranial section of the internal carotid artery. For example, adistalmost section 223 of the elongated sheath body 222 is 2.5 to 5 cmand the overall sheath body 222 is 20 to 30 cm in length. In thisembodiment, the ratio of length of the flexible, distalmost section tothe overall length of the sheath body is one tenth to one quarter of theentire sheath body 222. In another embodiment, there is a transitionsection 225 between the distalmost flexible section and the proximalsection 231, in which the distalmost section is 2.5 to 5 cm, thetransition section is 2 to 10 cm and the overall sheath body 222 is 20to 30 cm. In this embodiment, the distalmost flexible section and thetransition section collectively form at least one sixth and at most onehalf the entire length of the sheath body.

Other embodiments are adapted to reduce, minimize or eliminate a risk ofinjury to the artery caused by the distal-most sheath tip facing andcontacting the posterior arterial wall. In some embodiments, the sheathhas a structure configured to center the sheath body tip in the lumen ofthe artery such that the longitudinal axis of the distal region of thesheath body is generally parallel with the longitudinal or center axisof the lumen of the vessel. In an embodiment shown in FIG. 6, the sheathalignment feature is an inflatable or enlargeable bumper, for example aballoon 608, located on an outer wall of the arterial access sheath 220.The balloon 608 may be increased in size to exert a force on inner thearterial that contacts and pushes the elongated body 222 of the aerialaccess sheath away from the arterial wall.

In another embodiment, the sheath alignment feature is one or moremechanical structures on the sheath body that can be actuated to extendoutward from the sheath tip. In an embodiment, the sheath body 222 isconfigured to be inserted into the artery such that a particular edge ofthe arterial access is against the posterior wall of the artery. In thisembodiment, the sheath alignment feature need only extend outward fromone direction relative to the longitudinal axis of the sheath body 222to lift or push the sheath tip away from the posterior arterial wall.For example, as shown in FIG. 6, the inflatable bumper 608 is a blisteron one side of the sheath body. In another example, the mechanicalfeature extends only on one side of the sheath body.

In another embodiment, at least a portion of the sheath body 222 ispre-shaped so that after sheath insertion the tip is more aligned withthe long axis of the vessel, even at a steep sheath insertion angle. Inthis embodiment the sheath body is generally straight when the dilatoris assembled with the sheath during sheath insertion over the sheathguide wire, but once the dilator and guidewire are removed, thedistalmost section of the sheath body assumes a curved or angled shape.In an embodiment, the sheath body is shaped such that the distalmost 0.5to 1 cm section is angled from 10 to 30 degrees, as measured from themain axis of the sheath body, with a radius of curvature about 0.5″. Toretain the curved or angled shape of the sheath body after having beenstraightened during insertion, the sheath may be heat set in the angledor curved shape during manufacture. Alternately, the reinforcementstructure may be constructed out of nitinol and heat shaped into thecurved or angled shape during manufacture. Alternately, an additionalspring element may be added to the sheath body, for example a strip ofspring steel or nitinol, with the correct shape, added to thereinforcement layer of the sheath.

In an alternate embodiment, there are procedures in which it isdesirable to minimize flow resistance through the access sheath such asdescribed in U.S. Pat. No. 7,998,104 to Chang and U.S. Pat. No.8,157,760 to Criado, which are both incorporated by reference herein.FIG. 7 shows such an embodiment of the sheath body 222 where the sheathbody has stepped or tapered configuration having a reduced diameterdistal region 705 (with the reduced diameter being relative to theremainder of the sheath). The distal region 705 of the stepped sheathcan be sized for insertion into the carotid artery, typically having aninner diameter in the range from 0.065 inch to 0.115 inch with theremaining proximal region of the sheath having larger outside andluminal diameters, with the inner diameter typically being in the rangefrom 0.110 inch to 0.135 inch. The larger luminal diameter of theremainder of the sheath body minimizes the overall flow resistancethrough the sheath. In an embodiment, the reduced-diameter distalsection 705 has a length of approximately 2 cm to 4 cm. The relativelyshort length of the reduced-diameter distal section 705 permits thissection to be positioned in the common carotid artery CCA via atranscarotid approach with reduced risk that the distal end of thesheath body will contact the bifurcation B. Moreover, the reduceddiameter section also permits a reduction in size of the arteriotomy forintroducing the sheath into the artery while having a minimal impact inthe level of flow resistance. Further, the reduced distal diametersection may be more flexible and thus more conformal to the lumen of thevessel.

In some instances it is desirable for the sheath body 222 to also beable to occlude the artery in which it is positioned, for examples inprocedures that may create distal emboli. In these cases, occluding theartery stops antegrade blood flow in the artery and thereby reduces therisk of distal emboli that may lead to neurologic symptoms such as TIAor stroke. FIG. 8 shows an embodiment of an arterial access sheath 220with an inflatable balloon 805 on a distal region that is inflated viaan inflation line 810 that connects an internal inflation lumen in thesheath body 222 to a stopcock 229 which in turn may be connected to aninflation device. In this embodiment, there is also a Y-arm 815 that maybe connected to a passive or active aspiration source to further reducethe risk of distal emboli.

In some instances it is desirable to move the hemostasis valve away fromthe distal tip of the sheath, while maintaining the length of theinsertable sheath body 222 of the sheath. This embodiment is configuredto move the hands of the operator, and in fact his or her entire body,away from the target site and therefore from the image intensifier thatis used to image the target site fluoroscopically, thus reducing theradiation exposure to the user during the procedure. Essentially, thislengthens the portion of the arterial access sheath 220 that is outsidethe body. This portion can be a larger inner and outer diameter than thesheath body 222. In instances where the outer diameter of the catheterbeing inserted into the sheath is close to the inner diameter of thesheath body, the annular space of the lumen that is available for flowis restrictive. Minimizing the sheath body length is thus advantageousto minimize this resistance to flow, such as during flushing of thesheath with saline or contrast solution, or during aspiration or reverseflow out of the sheath. In an embodiment, as shown in FIG. 9, thearterial access sheath 220 has an insertable, elongated sheath body 222(i.e. the portion configured to insert into the artery) and a proximalextension portion 905. In an embodiment, the sheath body 222 has aninner diameter of about 0.087″ and an outer diameter of about 0.104″,corresponding to a 6 French sheath size, and the proximal extension hasan inner diameter of about 0.100″ to 0.125″ and an outer diameter ofabout 0.150″ to 0.175″. In another embodiment, the sheath body 222 hasan inner diameter of about 0.113″ and an outer diameter of about 0.136″,corresponding to an 8 French sheath size, and the proximal extension hasan inner diameter of about 0.125″ and an outer diameter of about 0.175″.In yet another embodiment, the sheath body 222 is stepped with a smallerdiameter distal section 705 to further reduce flow restriction, as inFIG. 7. In an embodiment, the proximal extension 905 is a lengthsuitable to meaningfully reduce the radiation exposure to the userduring a transcarotid access procedure. For example, the proximalextension 905 is between 10 and 25 cm, or between 15 and 20 cm.Alternately, the proximal extension 905 has a length configured toprovide a distance of between about 30 cm and 60 cm between thehemostasis valve 226 and the distal tip of the sheath body, depending onthe insertable length of the access sheath. A connector structure 915can connect the elongated sheath body 222 to the proximal extension 905.In this embodiment, the connector structure 915 may include a sutureeyelet 920 and/or ribs 925 to assist in securing the access sheath tothe patient. In an embodiment, the hemostasis valve 226 is a staticseal-type passive valve. In an alternate embodiment the hemostasis valve226 is an adjustable-opening valve such as a Tuohy-Borst valve 227 orrotating hemostasis valve (RHV). Alternately, the proximal extension mayterminate on the proximal end in a female Luer adaptor to which aseparate hemostasis valve component may be attached, either a passiveseal valve, a Tuohy-Borst valve or rotating hemostasis valve (RHV).

Typically, vessel closure devices require an arterial access sheath witha maximum distance of about 15 cm between distal tip of the sheath bodyto the proximal aspect of the hemostasis valve, with sheath body 222 ofabout 11 cm and the remaining 4 cm comprising the length of the proximalhemostasis valve; thus if the access sheath has a distance of greaterthan 15 cm it is desirable to remove the proximal extension 905 at theend of the procedure. In an embodiment, the proximal extension 905 isremovable in such a way that after removal, hemostasis is maintained.For example a hemostasis valve is built into the connector 915 betweenthe sheath body 222 and the proximal extension 905. The hemostasis valveis opened when the proximal extension 905 is attached to allow fluidcommunication and insertion of devices, but prevents blood flowing outof the sheath when the proximal extension 905 is removed. After theprocedure is completed, the proximal extension 905 can be removed,reducing the distance between the proximal aspect of the hemostasisvalve and sheath tip from greater than 15 cm to equal or less than 15 cmand thus allowing a vessel closure device to be used with the accesssheath 220 to close the access site.

In some procedures it may be desirable to have a low resistance (largebore) flow line or shunt connected to the access sheath, such asdescribed in U.S. Pat. No. 7,998,104 to Chang and U.S. Pat. No.8,157,760 to Criado, which are both incorporated by reference herein.The arterial sheath embodiment shown in FIG. 10 has a flow line 1005with internal lumen to a Y-arm 1015 of the connector 915. This flow linehas a lumen fluidly connected to a lumen in the sheath body. The flowline 1005 may be connected to a lower pressure return site such as avenous return site or a reservoir. The flow line 1005 may also beconnected to an aspiration source such as a pump or a syringe. In anembodiment, an occlusion element may also be included on the distal endof the sheath body 222, for example an occlusion balloon. This may bedesirable in percutaneous procedures, where the vessel cannot beoccluded by vascular surgical means such as vessel loops or vascularclamps.

In some procedures, it may be desirable to limit the amount of sheathbody insertion into the artery, for example in procedures where thetarget area is very close to the arterial access site. In a stentprocedure of the carotid artery bifurcation, for example, the sheath tipshould be positioned proximal of the treatment site (relative to theaccess location) so that it does not interfere with stent deployment orenter the diseased area and possibly cause emboli to get knocked loose.In an embodiment of arterial sheath 220 shown in FIGS. 11A and 11B, asheath stopper 1105 is slidably connected or mounted over the outside ofthe distal portion of the sheath body (see also FIGS. 11C and 11D). Thesheath stopper 1105 is shorter than the distal portion of the sheath,effectively shortening the insertable portion of the sheath body 222 bycreating a positive stop at a certain length along the sheath body 222.The sheath stopper 1105 may be a tube that slidably fits over the sheathbody 222 with a length that, when positioned on the sheath body 222,leaves a distal portion of the sheath body exposed. This length can bein the range 2 to 4 cm. More particularly, the length is 2.5 cm. Thedistal end of the sheath stopper 1105 may be angled and oriented suchthat the angle sits flush with the vessel and serves as a stop againstthe arterial wall when the sheath is inserted into the artery when thevessel is inserted into the artery, as shown in FIG. 11A. Alternately,the distal end of the sheath stopper may be formed into an angled flange1115 that contacts the arterial wall, as shown in FIGS. 11B, 11C, and11D. The flange 1115 is rounded or has an atraumatic shape to create amore positive and atraumatic stop against the arterial wall. The sheathstopper 1105 may be permanently secured to the arterial sheath, forexample the proximal end of the sheath stopper may be adhered toconnector 915 of the arterial access sheath. Alternately, the sheathstopper 1105 may be removable from the arterial access sheath 220 by theuser so it can be optionally utilized in a procedure. In this instance,the sheath stopper 1105 may have a locking feature 1110 on the proximalportion that engages with a corresponding locking features on theconnector 915, for example slots or recesses on the proximal sheathstopper engaging protrusions on the connector. Other locking featuresmay also be utilized.

Again with respect to FIG. 11C-11D, the sheath stopper 1105 can includeone or more cutouts, indents, or recessed grooves 1120 a or otherfeatures along a length of the sheath stopper 1105, for example alongthe anterior surface of the sheath stopper 1105. The grooves 1120 a canbe sized to receive sutures used to secure the sheath 220 to the patientto improve sheath stability and mitigate against sheath dislodgement.The one or more recessed grooves 1120 a on the sheath stopper 1105 canextend along an arc around the longitudinal axis of the sheath stopper1105. The one or more recessed grooves 1120 a on the anterior surfacecan alternate or be in a staggered pattern with corresponding one ormore recessed grooves 1120 b on the posterior surface of the sheathstopper 1105 to provide additional flexibility to the sheath assembly inthe anterior-to-posterior plane while maintaining axial strength toallow forward force of the sheath stopper against the arterial wall.Increased flexibility of the sheath assembly can reduce the amount ofstress that may be placed on a vessel. In some implementations, a visualindicator 1125 can be positioned on the anterior surface of the sheathstopper 1105. The visual indicator 1125 can be pad-printed text, line,or other pattern. The visual indicator 1125 can be molded directly intothe body of the sheath stopper 1105. The indicator 1125 can provide anexternal visual reference for rotational orientation of the sheathstopper (and thereby orientation of the distal flange 1115) with respectto the vessel. In use, the indicator 1125 can face anteriorly withrespect to the patient. Using this orientation, the distal flange 1115can lie approximately flat against the anterior wall of the vessel, e.g.the common carotid artery. Additional features the sheath stopper 1105may incorporate are described in U.S. Publication No. 2016/0296690,which is incorporated by reference herein.

As mentioned above, the access sheath 220 may include a radiopaque tipmarker 230. The access sheath 220 can also incorporate one or moremarkers 265 positioned on the sheath body 222 (see FIG. 11E) providingexternal visual guidance during insertion of the sheath 220 withoutspecial imaging to assess depth of insertion, as will be described inmore detail below. In some implementations, the markers 265 can be padprinted markers that designate insertion depths in increments of 1 cm upto about 5 cm. The external visual reference markers 265 on the sheathbody 222 can supplement the radiopaque tip marker 230 and the physicaldepth limit provided by the sheath stopper 1105. The external visualreference markers 265 can be useful, for example, when a user wants toinsert the sheath 220 to a shallower depth than prescribed by the sheathstopper 1105 or when a user removes the sheath stopper 1105 from thesheath body 222.

In situations where the insertion of the sheath body is limited tobetween 2 and 3 cm, and particularly when the sheath body is inserted ata steep angle, the sheath may conform to a bayonet shape when secured tothe patient. For example, the bayonet shape may comprise a first portionthat extends along a first axis and a second portion that extends alonga second axis that is axially offset from the first axis and/ornon-parallel to the first axis. The springiness of the sheath bodycauses this shape to exert a force on the vessel at the site ofinsertion and increase the tendency of the sheath to come out of thevessel if not properly secured. To reduce the stress on the vessel, thesheath stopper may be pre-shaped into a curved or bayonet shape so thatthe stress of the sheath body when curved is imparted onto the sheathstopper rather than on the vessel. The sheath stopper may be made fromspringy but bendable material or include a spring element such as astainless steel or nitinol wire or strip, so that when the dilator isinserted into the sheath and sheath stopper assembly, the sheath isrelatively straight, but when the dilator is removed the sheath stopperassumes the pre-curved shape to reduce the force the sheath imparts onthe vessel wall. Alternately, the sheath stopper may be made ofmalleable material or include a malleable element such as a bendablemetal wire or strip, so that it can be shaped after the sheath isinserted into a desired curvature, again to reduce the stress the sheathimparts on the vessel wall.

Sheath Dilator

With reference again to FIG. 2, the sheath dilator 260 is a component ofthe transcarotid access sheath system 200. The sheath dilator 260 is anelongated body that is inserted into the artery and enables smoothinsertion of the access sheath 220 over the sheath guidewire 300 througha puncture site in the arterial wall. Thus, the distal end of thedilator 260 is generally tapered to allow the dilator to be insertedover the sheath guidewire 300 into the artery, and to dilate the needlepuncture site to a larger diameter for insertion of the access sheath220 itself. To accommodate these functions, the dilator 260 has atapered end 268 with a taper that is generally between 6 and 12 degreestotal included angle (relative to a longitudinal axis of the dilator),with a radiused leading edge. Sheath dilators are typically locked tothe access sheath when assembled for insertion into the artery. Forexample a proximal hub 264 of the sheath dilator 260 is structured tosnap into or over a corresponding structure on the hemostasis valve 226of the arterial access sheath 220. An inner lumen of the dilator 260accommodates a sheath guidewire 300, with an inner diameter of between0.037 to 0.041″, depending on the sheath guide wire size for example.

For a transcarotid access sheath system 200, it may be desirable to makethe distal section of the sheath dilator 260 more flexible, tocorrespond with an increased flexible section of the access sheath 220.For example, the distal 2 to 5 cm of the sheath dilator 260 may be 20%to 50% more flexible than the proximal portion of the sheath dilator260. This embodiment would allow a sheath and dilator being inserted toaccommodate a steep insertion angle, as is often the case in atranscarotid access procedure, with a smoother insertion over theguidewire while still maintaining columnar support of the dilator. Thecolumnar support is desirable to provide the insertion force required todilate the puncture site and insert the access sheath.

For some transcarotid access sheath systems, it may be desirable to alsouse a smaller diameter access guidewire (for example in the range 0.014″to 0.018″ diameter) to guide the sheath and dilator into the artery. Inthis embodiment, the sheath dilator tapered end 268 is configured toprovide a smooth transition from a smaller wire size to the accesssheath. In one variation, the sheath guide wire is 0.018″ and the innerdilator lumen is in the range 0.020″-0.022″. In another variation, thesheath guide wire is 0.014″ and the inner dilator lumen is in the range0.016″ to 0.018″. The taper is similarly modified, for example the taperlength is longer to accommodate a taper from a smaller diameter to theinner diameter of the access sheath, or may comprise two taper angles toprovide a smooth transition from the smaller diameter wire to the accesssheath without overly lengthening the overall length of the taper.

In some procedures, it is desirable to position the distal tip of thesheath body 222 of the arterial access sheath 220 in the mid to distalcervical, petrous, or cavernous segments of the ICA as described above.These segments have curvature often greater than 90 degrees. In may bedesirable to have a sheath dilator with a softer and longer taper, to beable to navigate these bends easily without risk of injury to thearteries. However, in order to insert the sheath through the arterialpuncture, the dilator desirably has a certain stiffness and taper toprovide the dilating force. In an embodiment, the transcarotid accesssheath system 200 is supplied or included in a kit that includes two ormore tapered dilators 260A and 260B. The first tapered dilator 260A isused with the arterial access device to gain entry into the artery, andis thus sized and constructed in a manner similar to standard introducersheath dilators. Example materials that may be used for the tapereddilator include, for example, high density polyethylene, 72D Pebax, 90DPebax, or equivalent stiffness and lubricity material. A second tapereddilator 260B of the kit may be supplied with the arterial access devicewith a softer distal section or a distal section that has a lowerbending stiffness relative to the distal section of the first tapereddilator. That is, the second dilator has a distal region that is softer,more flexible, or articulates or bends more easily than a correspondingdistal region of the first dilator. The distal region of the seconddilator thus bends more easily than the corresponding distal region ofthe first dilator. In an embodiment, the distal section of the firstdilator 260A has a bending stiffness in the range of 50 to 100 N-mm² andthe distal section of the second dilator 260B has a bending stiffness inthe range of 5 to 15 N-mm².

The second dilator 260B (which has a distal section with a lower bendingstiffness) may be exchanged with the initial, first dilator such thatthe arterial access device may be inserted into the internal carotidartery and around curvature in the artery without undue force or traumaon the vessel due to the softer distal section of the second dilator.The distal section of the soft, second dilator may be, for example, 35or 40D Pebax, with a proximal portion made of, for example 72D Pebax. Anintermediate mid portion or portions may be included on the seconddilator to provide a smooth transition between the soft distal sectionand the stiffer proximal section. In an embodiment, one or both dilatorsmay have radiopaque tip markers so that the dilator tip position isvisible on fluoroscopy. In one variation, the radiopaque marker is asection of tungsten loaded Pebax or polyurethane which is heat welded tothe distal tip of the dilator. Other radiopaque materials may similarlybe used to create a radiopaque marker at the distal tip.

To facilitate exchange of the first dilator for the second dilator, oneor both dilators may be configured such that the distal section of thedilator is constructed from a tapered single-lumen tube, but theproximal portion of the dilator and any adaptor on the proximal end hasa side opening. FIG. 12 shows an example of a dilator 1205 formed of anelongated member sized and shaped to be inserted into an artery, and aproximal hub 1210. The dilator has a side opening 1215, such as a slot,that extends along at least a portion of the length of the dilator 1205such as along the elongated body and the proximal hub 1210. In anembodiment, the side opening 1215 is located only on a proximal regionof the dilator 1205 and through the proximal hub 1210 although this mayvary. The side opening 1215 provides access to an internal lumen of thedilator 1205, such as to insert and/or remove a guidewire into or fromthe lumen. An annular, movable sleeve 1220 with a slot on one side islocated at or near the proximal hub 1210 of the dilator 1205. The sleeve1220 may be moved, such as via rotation, about a longitudinal axis ofthe hub 1210, as described below. Note that the distal end of thedilator 1205 has a tapered configuration for dilating tissue.

FIG. 13 shows an enlarged view of the proximal region of the dilator1205. As mentioned, the dilator 1205 has a side opening 1215 in the formof a slot that extends along the length of the dilator 1205 and theproximal hub 1210. The sleeve 1220 is positioned around the outerperiphery of the dilator and is shaped such that it covers at least aportion of the side opening 1215. Thus, the sleeve 1220 can prevent aguidewire positioned inside the dilator 1205 from exiting the dilatorvia the side opening 1215. As mentioned, the sleeve 1220 is rotatablerelative to the dilator 1205 and proximal hub 1210. In the illustratedembodiment, the sleeve 1220 is rotatable about a longitudinal axis ofthe dilator 1205 although other types of relative movement are withinthe scope of this disclosure. As shown in FIG. 14, the sleeve 1220 has aslot 1225 that can be aligned with the side opening 1215. When alignedas such, the slot 1225 and side opening 1215 collectively provide anopening for a guidewire to be inserted or removed from the internallumen of the dilator 1205. The sleeve 1220 can be rotated between theposition shown in FIG. 13 (where it covers the side opening 1215) andthe position shown in FIG. 14 (where the side opening is uncovered dueto the slot 1225 being aligned with the side opening 1215.)

A method of use of this embodiment of an access sheath kit is nowdescribed. A sheath guide wire, such as an 0.035″ guidewire, is insertedinto the common carotid artery, either using a Modified Seldingertechnique or a micropuncture technique. The distal end of the guidewirecan be positioned into the internal or external carotid artery, or stopin the common carotid artery short of the bifurcation. The arterialaccess sheath with the first, stiffer dilator, is inserted over the0.035″ wire into the artery. The arterial access sheath is inserted suchthat at least 2.5 cm of sheath body 222 is in the artery. If additionalpurchase is desired, the arterial access sheath may be directed further,and into the internal carotid artery. The first dilator is removed whilekeeping both the arterial access sheath and the 0.035″ wire in place.The side opening 1215 in the proximal portion of the dilator allows thedilator to be removed in a “rapid exchange” fashion such that most ofthe guidewire outside the access device may be grasped directly duringdilator removal. The second dilator is then loaded on to the 0.035″ wireand inserted into the sheath. Again, a dilator with a side opening 1215in the proximal portion of the dilator may be used to allow the 0.035″wire to be grasped directly during guide wire insertion in a “rapidexchange” technique. Once the second dilator is fully inserted into thearterial access device, the arterial access sheath with the softertipped, second dilator is advanced up the internal carotid artery andaround bends in the artery without undue force or concern for vesseltrauma. This configuration allows a more distal placement of thearterial access sheath without compromising the ability of the device tobe inserted into the artery.

Alternately, one or more standard dilators may be used without sideopenings. If a standard dilator without a side opening is used, afterthe access device is inserted into the artery over a guide wire with thefirst dilator, the first dilator may be removed together with theguidewire, leaving only the access device in place. The second dilatorwith a guide wire preloaded into the central lumen may be insertedtogether into the arterial access device. Once fully inserted, theaccess device and second dilator with softer tip may be advanceddistally up the internal carotid artery as above. In this alternatemethod, the initial guide wire may be used with both dilators, or may beexchanged for a softer tipped guide wire when inserted with the secondsofter tipped dilator.

In some instances, it may be desirable to insert the access sheathsystem over an 0.035″ wire into the carotid artery, but then exchangethe wire to a smaller guidewire, in the range 0.014″ to 0.018″. Becausethe access into the carotid artery may require a steep angle of entry, awire that can offer good support such as an 0.035″ wire may be desirableto initially introduce the access sheath into the CCA. However, once thesheath is in the artery but the user would like to advance it furtherover a smaller guidewire, it may be desirable to exchange the 0.035″wire for a smaller guide wire. Alternately, the user may exchange boththe dilator and 0.035″ wire for a softer dilator and smaller guide wirein the range 0.014″ to 0.018″. Alternately, the user may wish toposition an 0.014″ guidewire which he or she will subsequently use tointroduce an interventional device, while the sheath and dilator arestill in place. The dilator may offer access and support for this guidewire, and in instances of severe access sheath angle may aid indirecting the wire away from the posterior wall of the artery so thatthe wire may be safely advanced into the vascular lumen without risk ofluminal injury.

In an embodiment as shown in FIG. 15, the sheath dilator 260 is atwo-part dilator assembly, with an inner dilator 269 and an outerdilator 270 that slidably attach to one another in a co-axialarrangement. Both dilators have proximal hubs 264 a and 264 b. When thetwo dilators are assembled together, the two hubs 264 a and 264 b havefeatures which allow them to be locked together, e.g. a snap fit or athreaded fit, so that the two dilators can be handled as one unit. In anembodiment, the inner dilator 269 has a proximal hub 264 b whichincludes a rotating coupler with internal threads that engage externalthreads on the proximal hub 264 a of the outer dilator 270. The innerdilator 269 effectively transforms the dilator assembly from an 0.035″or 0.038″ wire compatible dilator to an 0.018″ or 0.014″ wire compatibledilator, and extends out the distal end of the outer dilator. In anembodiment, shown in FIG. 16, the inner dilator has an angled tip 276that is bent or angled relative to a longitudinal axis of the remainderof the dilator. In an embodiment, the angle is a 45 degree angle. Thisangled tip 276 allows the user to direct the guidewire into one oranother branch vessel more easily. The inner dilator may have a taperedtip, straight as shown in FIG. 15 or an angled tip as shown in FIG. 16.Alternately, the inner dilator may have a constant outer diameter to thedistal end, with a rounded leading edge. In an embodiment, the innerdilator has a radiopaque marker 274 at or near the distal tip to aid invisualization of the dilator under fluoroscopy. In an embodiment, theinner dilator is reinforced to make it more torquable to aid indirecting the angled tip in a particular direction. For example thedilator may have a coil or braid reinforcement layer. Once theinterventional wire is positioned, the two-part dilator is removed andthe wire may then be used to insert interventional devices through thearterial sheath into the artery and advanced to the treatment site.

An alternate embodiment, shown in FIG. 17, allows two separate wiresizes to be used with the dilator. This embodiment includes a dilator1705 with two guide wire internal lumens that extend along the length ofthe device. FIG. 17 shows the distal end of this embodiment. As seenmore clearly in a cross sectional view FIG. 18, one lumen 1805 isconfigured for an 0.035″ or 0.038″ guidewire, and the other lumen 1815is for an 0.014″ to 0.018″ guide wire. In this embodiment, the largerlumen 1805 is centered around the centerline of the taper 268, whereasthe smaller lumen 1815 is offset from the centerline of the taper. Inthis configuration, the access sheath is introduced into the artery overthe larger guidewire, which is positioned in the larger lumen 1805. Oncepositioned, an interventional wire can be placed through the secondlumen 1815. The larger guidewire and dilator are then removed from theaccess sheath and the interventional wire may then be used to insertinterventional devices through the arterial sheath into the artery andadvanced to the treatment site as above.

Sheath Guidewire

Arterial access sheaths are typically introduced into the artery over asheath guidewire of 0.035″ or 0.038″ diameter. The inner diameter andtaper length of the distal tip of the dilator are sized to fit with sucha guidewire. Some sheaths, for example for radial artery access, aresized to accommodate a sheath guidewire of 0.018″ diameter, with acorresponding dilator having a distal tip inner diameter and taperlength. The sheath guidewire may have an atraumatic straight, angled, orJ-tip. The guidewire smoothly transitions to a stiffer segment on theproximal end. This configuration allows atraumatic entry and advancementof the wire into the artery while allowing support for the sheath whenthe sheath is introduced into the artery over the wire. Typically thetransition from the atraumatic tip is about 4 to 9 cm to the stiffersection. The sheath is usually inserted 15 to 20 cm into the artery, sothat the stiffer segment of the wire is at the arterial entry site whenthe sheath is being inserted.

However, in the case of a transcarotid access entry point, the amount ofwire that can be inserted is much less than 15 cm before potentiallycausing harm to the distal vessels. In a case of a transcarotid accessfor a carotid stent or PTA procedure, it is very important that the wireinsertion length is limited, to avoid risk of distal emboli beinggenerated by the sheath guide wire at the site of carotid arterydisease. Thus it is desirable to provide a guide wire that is able toprovide support for a potentially steep sheath entry angle while beinglimited in length of insertion. In an embodiment, a transcarotid sheathguidewire has an atraumatic tip section but has a very distal and shorttransition to a stiffer section. For example, the soft tip section is1.5 to 2.5 cm, followed by a transition section with length from 3 to 5cm, followed by a stiffer proximal segment, with the stiffer proximalsection comprising the remainder of the wire. In some implementations,the soft tip section (i.e. the distalmost flexible section including thedistal tip of the guidewire) is between 1 cm and 2 cm and the transitionsection positioned between the flexible distalmost section and the morerigid core section extending proximally from the transition section isbetween 3 cm and 5 cm.

The sheath guidewire may have guide wire markings 318 to help the userdetermine where the tip of the wire is with respect to the dilator. Forexample, there may be a marking on the proximal end of the wirecorresponding to when the tip of the wire is about to exit the microaccess cannula tip. This marking would provide rapid wire positionfeedback to help the user limit the amount of wire insertion. In anotherembodiment, the wire may include an additional mark to let the user knowthe wire has exited the cannula by a set distance, for example 5 cm.

Micro Access Components

With reference to FIG. 1, a micro access kit 100 for initialtranscarotid access includes an access needle 120, an access guidewire140, and a micro access cannula 160. The micro access cannula 160includes a body 162 and an inner dilator 168 slidably positioned withina lumen of the body 162. Typically for arterial access, the initialneedle puncture may be with a 21 G or 22 G access needle, or an 18 Gneedle if the Modified Seldinger technique is used. For transcarotidaccess, it may be desirable to access with an even smaller needlepuncture. Percutaneous access of the carotid artery is typically morechallenging than of the femoral artery. The carotid artery is athicker-walled artery, it is surrounded by a tissue sleeve known as thecarotid sheath, and it is not anchored down as much by surroundingmusculature, therefore the initial needle stick is more difficult andmust be done with more force, onto an artery that is less stable, thusincreasing the risk of mis-placed puncture, arterial dissection, or backwall puncture. A smaller initial needle puncture, for example a 23 G or24 G needle, increases the ease of needle entry and reduce these risks.The sheath guidewire should be accordingly sized to fit into the smallerneedle, for example a 0.016″ or 0.014″ wire. The access needle 120 mayinclude a textured surface on the distal end to render it visible onultrasound, to aid in ultrasound-guided insertion of the needle into theartery. The needle length may be in a range from 4 cm to 8 cm in length.

As best shown in FIGS. 19A and 19B, the access needle 120 may alsoinclude a visible depth indicator 124 located near the distal end of theneedle shaft. The visible depth indicator 124 can be visible to the userwithout the help of ultrasound or radiography, or other imaginingtechniques, providing the user with a reference during needle insertionand manipulation of the guidewire during direct insertions into thevessel. The access needle 120, which can be a 21 G, 22 G, 23 G, or 24 Gneedle, can have an elongate shaft defining an inner lumen and coupledto a proximal hub 122. The shaft length from the distal end of needlehub 122 to the distal tip of its shaft can be between 30 mm to about 100mm. In some implementations, the shaft length is approximately 40 mm or70 mm. The visible depth indicator 124 can be positioned on the elongateshaft of the needle 120 a distance D away from the distal tip of theneedle 120, for example about 3 mm to about 7 mm, or preferably 4.5 mmto 5 mm. In some implementations, the depth indicator 124 can have awidth W of approximately 1 mm to about 2 mm such that the indicator 124is readily visible to the naked eye during use, such as direct accessinto the common carotid artery (CCA). Presence of the depth indicator124 reduces the risk that the operator will advance the access needle120 into or through the opposite wall of the vessel. Advancement of theneedle 120 into the vessel can be metered visually by assessingadvancement of the depth indicator 124 into the vessel, which is a knowndistance away from the distal tip. The depth indicator 124 can becreated using chemical etch, laser-etching, pad printing or othermarking methods.

Access guidewires typically used in micropuncture kits can haverelatively long distal floppy sections, for example between 30-50 mmlong. However in some applications, such as transcarotid arteryrevascularization (TCAR), the operator may want to advance the guidewireinto the vessel only 30-40 mm to avoid advancing the tip of theguidewire into a diseased section of the artery. For guidewires withlong distal floppy sections, inserting only the first 30-40 mm of theguidewire means the supportive section of the guidewire remains outsidethe vessel and only the non-supportive portion of the guidewire isavailable for advancing the cannula and dilator. Advancing themicroaccess cannula and dilator over the non-supportive section of theguidewire carries a higher risk of causing damage to the inner surfaceof the vessel. Therefore, the access guidewires described herein have ashorter, distal floppy section that allows for a shorter length to beinserted within the vessel while still ensuring the more rigid proximalsupport section is available within the vessel for advancement of thecannula and dilator over it.

The guidewire 140 described herein can have a shorter distalmostflexible section terminating in a distal tip, for example, a flexiblesection that is just 1 cm to 2 cm long. A transition section proximal tothe distalmost flexible section transitions proximally in stiffnesstowards the stiffer core section extending proximally from thetransition section. Such micro access guidewires are typically 0.018″ indiameter, with a distalmost flexible section of about 1-2 cm, atransition section of 5-6 cm leading to the stiffer core sectionextending the remainder of the length of the guidewire. In anembodiment, a transcarotid access guidewire is from 0.014″ to 0.018″ indiameter, and has a distalmost flexible section of 1 cm, a transitionsection of 2-3 cm to bring the stiff supportive core section much closerto the distal tip. This will allow the user to have good support formicro access cannula insertion even in steep access angles andlimitations on wire insertion length.

As with the sheath guidewire, the micro access guidewire 140 may have atleast one guidewire marking or depth indicator 143 visible to the nakedeye that is positioned a known distance from the distal tip of theguidewire 140 to help the user determine where the tip of the guidewire140 is with respect to the vessel as well as other components of themicroaccess system 100, e.g. the access needle 120, the micro cannula160, and/or the inner dilator 168 (see FIGS. 1 and 19A). The depthindicator 143 can provide rapid, wire position feedback without anyspecial visualization techniques such as ultrasound or radiography tohelp the user limit the amount of wire insertion. For example, a depthindicator 143 can be located at a first location of the guidewire 140 adistance away from the distal tip of the guidewire 140 that when alignedwith another portion of the system 100, such as the proximal end of thecannula 160, corresponds to when the tip of the wire 140 is about toexit the micro cannula 160. In another embodiment, the guidewire 140 mayinclude an additional marking 143 to let the user know the guidewire 140is about to or has exited the dilator by a set distance, for example 5cm. In another embodiment, the guidewire 140 may include a furthermarking 143 positioned more distally to let the user know when theguidewire 140 is inserted through the access needle 120 the guidewire140 is about to exit the access needle 120 or has exited by a setdistance. Thus, the guidewire 140 can include a plurality of markings143 that together provide visual guidance related to the depth ofinsertion and the relative extension of the guidewire 140 in relation toother system components.

FIGS. 20A-20C illustrate an implementation of using at least one visibledepth indicator on the access guidewire 140 that when a portion of thedepth indicator is positioned relative to another portion of the system100 can provide the user with rapid, wire position feedback and meteringof the advancement of the guidewire 140 relative to the vessel and othercomponents of the system 100 without needing any special visualizationaside from the user's own eyes. This visual reference providesinformation regarding the distance the guidewire 140 extends beyond theaccess needle 120, for example, and into the vessel. The guidewire 140can include at least one visible depth indicator 143 a known distance Dfrom a distal-most end or distal tip of the guidewire 140. The visibledepth indicator 143 can have a known width W extending between aproximal edge and a distal edge of the indicator 143. For example, onedepth indicator 143 can be 2 cm wide and the distal edge of the depthindicator 143 positioned 10 cm from the distal tip of the guidewire 140such that the proximal edge of the depth indicator 143 is positioned 12cm from the distal tip of the guidewire 140. The distance away from thedistal tip of the guidewire 140 is measured from the distal tip of theguidewire 140 to a distal edge of the at least one visible depthindicator 143. When the access guidewire is inserted through the innerlumen of the elongate shaft of the access needle 120 aligning the distaledge of the depth indicator 143 with a back end of the proximal hub 122of the access needle 120 extends the distal tip of the guidewire 140beyond the distal tip of the elongate shaft a certain extension length.Further advancing the access guidewire 140 through the inner lumen ofthe elongate shaft of the access needle 120 until the proximal edge isaligned with the back end of the proximal hub 122 of the needle 120extends the distal tip of the guidewire 140 beyond the distal tip of theelongate shaft of the access needle 120 the extension length plus thewidth of the depth indicator 143. For example, the needle 120 throughwhich the guidewire 140 is advanced can measure 7 cm from the back endof the proximal hub 122 to the distal tip of the needle. Advancing theguidewire 140 through the access needle 120 until the distal edge of thedepth indicator aligns with the back end of the needle hub 122 providesan extension length 141 of the guidewire 140, a portion of the guidewire140 extending distal to the distal tip of the needle 120, that is 3 cmlong (see FIG. 20B). Advancing the guidewire 140 through the needle 120until the proximal edge of the depth indicator is aligned with the backend of the needle hub 122 provides an extension length 141 of theguidewire 140 distal to the distal tip of the needle 120 that is anadditional 2 cm or a total of 5 cm long (see FIG. 20C). It should beappreciated that the guidewire 140 may have multiple discrete markings143 to indicate various extension lengths 141 and thus depths in thevessel (e.g. 1 cm, 2 cm, 3 cm, etc.) The one or more markings 143 can becreated by chemical etch, laser marking, pad printing, or other methods.

Typically, the micro access cannula 160 includes a cannula body 162configured to receive an inner dilator 168 through its lumen, thedilator 168 having a tapered tip. The inner dilator 168 provides asmooth transition between the cannula 160 and the access guide wire 140.The cannula 160 is sized to receive the 0.035″ wire, with inner diameterin the range about 0.037″ to about 0.041″. In an embodiment, a microaccess cannula 160 is configured for transcarotid access. For example,the dilator 168 of the cannula 160 may be sized for a smaller 0.014″access guide wire 140. Additionally, the cannula 160 may have one ormore visible depth indicators 165 to aid the user in assessing theamount of insertion of the cannula 160 without any special imaging asidefrom the naked eye, as will be described in more detail below. Aradiopaque material (e.g. barium, bismuth, tungsten) can be added to theentire shaft polymer of the micro access cannula 160 and/or dilator 168to provide visibility during fluoroscopy. Alternatively or additionallythe micro access cannula 160 and/or the dilator 168 can have one or moreradiopaque markers 164, for example, at the distal tip of the cannula162 or dilator 168, to help the user visualize the tip location underfluoroscopy. This is useful for example in cases where the user may wantto position the cannula in the ICA or ECA, for example.

As shown in FIGS. 21A-21B, the microaccess cannula 160 can include aplurality of depth indicators 165 having a known width W and positioneda known distance D from the distal-most tip of the cannula 160. Each ofthe plurality of visible depth indicators 165 can identify a distancefrom the distal tip of the cannula 160. The indicators 165 can providerapid metering of the advancement of the cannula 160 relative to theinsertion point into the vessel as well as other components of thesystem 100 without any special visualization such as ultrasound orradiography. Additionally or alternatively, each of the plurality ofvisible depth indicators 165 can be formed by a number of marks 2165such as circumferential rings. Although the marks 2165 are describedherein as being circumferential rings it should be appreciated that themarks 2165 need not completely encircle the cannula and can take onother shapes such as dots, dashes, or other visible marks.

Each depth indicator 165 has at least one mark 2165. The number of marks2165 forming each of the plurality of depth indicators 165 can identifythe number of increments that the depth indicator 165 is positioned fromthe distal tip of the cannula 160. This allows for the total distance tobe readily and easily surmised simply by looking at the number of marks2165 making up each depth indicator 165. In other words, each depthindicator 165 can indicate the distance it is from the distal tip of thecannula 160 based on the number of marks 2165 (whether dots, dashes,bands or circumferential rings) forming the particular depth indicator165. For example, as best shown in FIGS. 21A-21B, a first depthindicator 165 a can be formed by a single circumferential ring 2165positioned such that a center of the ring 2165 is a first distance fromthe distal tip (e.g. 10 mm). A second depth indicator 165 b can beformed by two circumferential rings 2165 positioned such that a centerbetween the pair of rings 2165 is a second distance from the distal tip(e.g. 20 mm). A third depth indicator 165 c can be formed by threecircumferential rings 2165 positioned such that a center of the threerings 2165 is a third distance from the distal tip (e.g. 30 mm). Afourth depth indicator 165 d can be formed by four of thecircumferential rings 2165 positioned such that a center of the four isa fourth distance from the distal tip (e.g. 40 mm). The depth indicators165 can continue in this pattern thereby metering the distance from thedistal tip by standard increments in a way that is readily visible andinstantaneously understandable to the user.

It should be appreciated that the measured distance need not be from thedistal tip to the center of the rings as described above, but insteadcan be from the distal tip to a distal edge of the mark(s) 2165 or fromthe distal tip to a proximal edge of the mark(s) 2165. Additionally, oneof the depth indicators 165 e can be a solid marker of a known width,the middle of which (or distal edge or proximal edge) identifies a knowndistance from the distal tip of the cannula 160 that is generallyconsidered an upper depth limit. In some implementations, the microaccess cannula 160 is only inserted between 20-30 mm and an upper depthlimit can be generally around 50 mm. These distances can vary and moreor fewer depth indicators 165 are considered herein. For example, ifadditional external depth indicators 165 are desired the markerincrements can be identified by patterns of mark such as 1 mark, 2marks, 3 marks, 4 marks, solid band, as described above and thenstarting over with 1 mark, 2 marks, 3 marks, 4 marks, solid band, and soon. The solid band breaking up the mark pattern provides a quick andeasily identifiable indication that the fifth marker increment in theseries has been reached without requiring a user to count too manyrings. For example, more than 4 marks per depth indicator 165 can betedious to differentiate and lead to reading errors by the user.Additionally, an increment size of 10 mm is generally easy to calculatequickly. It should be appreciated, however, that other increment sizesare considered such as 5 mm, 15 mm, or even 20 mm for longer cannulas.One or more of the depth indicators 165 can be distinguishable based onits color as well as by the number and/or pattern of marks. For example,a first mark can be a first color, a second mark can be a second color,a third mark can be third color and so on. The marks can be easilydistinguishable colors indicating depth of insertion (e.g. white,yellow, orange, red, green, blue, black, etc.) The marks can be within asimilar color family, but have an increasing intensity or tone todistinguish the depth of insertion (e.g. a first mark being pale pinktowards a last mark being deep red).

The depth indicators 165 may be created by pad printing, laser marking,additions of colorant to the cannula material, or other methods. Othercomponents of the micro access kit 100 can include similar meteringmarkings as described above. For example, the depth indicators 143 ofthe guidewire 140 may also be metered to indicate distance from thedistal tip depending on the number of marks (or color, size, shape) perindicator 143. As described above, the sheath body 220 and/or the sheathstopper 1105 can incorporate one or more markings that provide anindication of the depth of insertion of the sheath 220.

Exemplary Kits:

Any or all of the devices described above may be provided in kit form tothe user such that one or more of the components of the systems areincluded in a common package or collection of packages. An embodiment ofan access sheath kit comprises an access sheath, sheath dilator, andsheath guidewire all configured for transcarotid access as describedabove.

In an embodiment, a micro access kit comprises an access needle, a microaccess guide wire, and a micro access cannula and dilator wherein theguidewire is 0.014″ and the micro access cannula and dilator are sizedto be compatible with the 0.014″ guide wire.

In an embodiment, an access kit comprises the access sheath, sheathdilator, sheath guide wire, access needle, micro access guide wire andmicro access cannula and dilator, all configured for transcarotidaccess.

In an alternate embodiment, the access guidewire is also used as thesheath guide wire. In this embodiment, the access kit comprises anaccess needle, access guide wire, access sheath and dilator. The sheathand dilator use the access guide wire to be inserted into the vessel,thereby avoiding the steps required to exchange up to a larger sheathguidewire. In this embodiment, the dilator taper length and inner lumenis sized to be compatible with the smaller access guide wire. In oneembodiment, the access guide wire is 0.018″. In an alternate embodimentthe access guide wire is 0.016″. In an alternate embodiment, the accessguide wire is 0.014″.

Exemplary Methods:

There are now described exemplary methods of use for a transcarotidaccess system. In an exemplary transcarotid procedure to treat a carotidartery stenosis, the user starts by performing a cut down to the commoncarotid artery. The user then inserts an access needle 120 into thecommon carotid artery at the desired access site. An access guide wire140 with a taper configured for transcarotid access is inserted throughthe needle into the common carotid artery and advanced into the CCA. Theaccess needle 120 is removed and a micro access cannula 160 is insertedover the wire 140 into the CCA. The micro access cannula is inserted adesired depth using the marks 165 on the cannula as a guide, to preventover insertion.

The user removes the cannula inner dilator 168 and guide wire 140,leaving the cannula 162 in place. If desired, the user performs anangiogram through the cannula 162. The user then places sheath guidewire 300 through the cannula, using guide wire markings 318 to aid ininserting the wire to a desired insertion length. The cannula 162 isremoved from the guidewire and the access sheath 220 and sheath dilator260 are inserted as an assembly over the sheath guidewire 300 into theCCA. The sheath stopper flange 1115 of the sheath stopper 1105 limitsthe insertion length of the arterial sheath. Once positioned, thedilator 260 and guidewire 300 are removed. The sheath is then sutured tothe patient using the securing eyelets 234, ribs 236, and/or suturegrooves 1120 a. An interventional procedure is then performed byintroduction of interventional devices through hemostasis valve 226 onthe proximal end of the arterial sheath and to the desire treatmentsite. Contrast injections may be made as desired during the procedurevia the flush arm 228 on the arterial sheath 220.

Alternately, the user inserts an access needle 120 directly into thecommon carotid artery at the desired access site visually monitoring adepth indicator 124 on the needle 120. Vessel wall thickness istypically 1-2 mm and the vessel diameter of the common carotid artery istypically 8-9 mm. Thus, maintaining the depth indicator 124 positioned 5mm from the distal tip in view outside the vessel ensures the distancethe needle is inserted will penetrate the wall thickness fully withoutcontacting the back side of the vessel wall.

Alternately or additionally, an access guidewire 140 configured fortranscarotid access is inserted through the hub 122 of the needle 120until a portion of the depth marker 143 aligns with another portion ofthe needle 120 identifying a desired amount of extension length 141 ofthe guidewire 140 is positioned within the common carotid artery. Forexample, the proximal edge of the depth marker 143 on the guidewire 140can be aligned with the back end of the needle hub 122 indicating 5 cmof wire has been advanced beyond the distal tip of the needle 120 intothe common carotid artery. Alternatively, the distal edge of the depthmarker 143 is aligned with the back end of the needle hub 122 indicating3 cm of wire beyond the distal tip of the needle into the common carotidartery.

Leaving the access guidewire 140 in place, the access needle 120 iscarefully withdrawn from the vessel. The micropuncture cannula 160having the inner dilator 168 extending through its lumen is advancedover the access guidewire 140 into the vessel through the puncture. Thedepth markings 165 of the micropuncture cannula 160 are monitoredvisually by the user to confirm desired depth of micropuncture cannulainsertion and to prevent over-insertion. The micropuncture cannula 160is left in place once desired depth is reached, and the dilator 168 andaccess guidewire 140 are carefully withdrawn.

Alternately, the sheath guidewire 300 is placed into the CCA via asingle needle puncture with a larger access needle, for example an 18 Gneedle. In this embodiment, the access cannula and access guide wire arenot needed. This embodiment reduces the number of steps required toaccess the artery, and in some circumstances may be desirable to theuser.

Alternately, the sheath dilator is a two-part sheath dilator assembly260 as shown in FIG. 15, with an inner dilator 269 and an outer dilator270. The outer dilator 270 is configured to receive an 0.035″ sheathguide wire 300 and to provide a smooth transition from the 0.035″ wireto the access sheath 220. The inner dilator 269 is configured to receivea smaller guide wire in the range 0.014″ to 0.018″ and to provide asmooth transition from the smaller guide wire to the outer dilator 270.Once the sheath guidewire is positioned in the CCA, the access sheathand outer sheath dilator 270 are inserted over an 0.035″ sheathguidewire 300 into the CCA. The guidewire is then removed and an innersheath dilator 269 is inserted into the outer sheath dilator. In anembodiment, the inner sheath dilator has an angled tip 276 as seen inFIG. 16. An interventional 0.014″ guide wire is inserted through theinner sheath dilator and is directed to the target treatment site usingthe angled tip to aid in guide wire positioning. Alternately, the innersheath dilator has a straight tip and is used to aid in positioning theguide wire safely into the CCA. Once the 0.014″ wire is positioned at oracross the target treatment site, the sheath dilator 260 and sheath0.035″ guide wire 300 are then removed, and the intervention proceeds.

In an alternate embodiment, the sheath dilator is a two lumen sheathdilator 1705. In this embodiment, the sheath and dilator are insertedover the sheath guide wire 300, with the sheath guidewire positioned inthe larger lumen 1805 of dilator 1705. Once the sheath and dilator is inplace, an interventional 0.014″ guide wire is positioned through thesmaller lumen 1815. The dilator provides distal support and maintainsthe position of the sheath tip in the axial direction of the vessellumen, thus allowing a potentially safer and easier advancement of the0.014″ wire than if the dilator were removed and the sheath tip wasdirected at least partially towards to posterior wall of the artery.Once the 0.014″ wire is positioned at or across the target treatmentsite, the sheath dilator 1705 and sheath guide wire 0.035″ are thenremoved, and the intervention proceeds.

In yet another embodiment, it may be desirable to occlude the CCA duringthe intervention to minimize antegrade flow of emboli. In thisembodiment, the occlusion step may be performed via vascular surgicalmeans such as with a vessel loop, tourniquet, or vascular clamp. In analternate embodiment, the access sheath 220 has an occlusion elementsuch as an occlusion balloon 805 on the distal tip. In this embodiment,the balloon is inflated when CCA occlusion is desired. In a furthervariant, while the CCA is occluded either surgically or via balloonocclusion, it may be desirable to connect the arterial sheath to a flowshunt, for example to create a reverse flow system around the area ofthe treatment site to minimize distal emboli. In this embodiment, thearterial sheath 220 has a Y connection to a flow line 1005. The flowline 1005 may be connected to a return site with a pressure lower thanarterial pressure to create a pressure gradient that results in reverseflow through the shunt, for example an external reservoir or a centralvenous return site like the femoral vein or the internal jugular vein.Alternately, the flow line may be connected to an aspiration source suchas an aspiration pump or syringe.

In another embodiment, a transcarotid access system is used to perform apercutaneous neurointerventional procedure. In this embodiment, the userperforms a percutaneous puncture of the common carotid artery CCA withan access needle 120 at the desired access site. Ultrasound may be usedto accurately identify a suitable access site and guide the needlepuncture. An access guide wire 140 is inserted through the needle intothe common carotid artery and advanced into the CCA. The access needle120 is removed and a micro access cannula 160 is inserted over the wire140 into the CCA. The user removes the cannula inner dilator 168 andguide wire 140, leaving the cannula 162 in place. If desired, the userperforms an angiogram through the cannula 162. The user then placessheath guide wire 300 through the cannula, using guide wire markings 318to aid in desired insertion length. The cannula 162 is removed from theguidewire and the access sheath 220 and sheath dilator 260 are insertedas an assembly over the sheath guidewire 300 into the CCA.

Alternately, the smaller access guide wire 140 is used to position theaccess sheath 220 and sheath dilator 260 into the CCA. In thisembodiment, the sheath dilator tapered tip 268 has been configured totransition smoothly from the access guide wire 140 to the access sheath220. In one variant, the access needle is 21 G and the access guide wireis 0.018″. In another variant, the access needle is 24 G and the accessguide wire is 0.014″. Once the sheath is placed, the guide wire andsheath dilator are removed and an interventional procedure is thenperformed by introduction of interventional devices through hemostasisvalve 226 on the proximal end of the arterial sheath and to the desiretreatment site. Contrast injections may be made as desired during theprocedure via the flush arm 228 on the arterial sheath 220.

Alternately, it may be desirable once the sheath is placed in the CCA toadvance it further into the ICA, for example in the mid to distalcervical ICA, petrous ICA or further distally. In this embodiment, thesheath dilator may be replaced with a softer sheath dilator so that thesheath may be advanced without risk of damaging the distal ICA. In thisembodiment, the softer dilator has a distal radiopaque marker so thatthe user may easily visualize the leading edge of the sheath and dilatorassembly during positioning of the sheath. Once the access sheath ispositioned, the dilator and sheath guide wire may be removed and theintervention can proceed. Alternately, once the sheath is placed in theCCA, the 0.035″ guide wire may be removed and an inner dilator with asmaller guidewire in the range 0.014″ to 0.018″ may be inserted intosheath dilator. The sheath dilator assembly with the inner dilator andsmaller guide wire may be then positioned more distally in the ICA withreduced risk of vessel trauma.

In an embodiment, it may be desirable to occlude the CCA or ICA duringportions of the procedure to reduce the chance of distal emboli flowingto the brain. In this embodiment, the CCA or ICA is occluded by means ofan occlusion balloon 805 on the access sheath 220. It may also bedesirable to connect the arterial sheath to a flow shunt, for example tocreate a reverse flow system around the area of the treatment site tominimize distal emboli. In this embodiment, the arterial sheath 220 hasa Y connection to a flow line 1005. The flow line may be connected to areturn site with a pressure lower than arterial pressure to create apressure gradient that results in reverse flow through the shunt.Alternately, the flow line may be connected to an aspiration source suchas an aspiration pump or syringe.

While this specification contains many specifics, these should not beconstrued as limitations on the scope of an invention that is claimed orof what may be claimed, but rather as descriptions of features specificto particular embodiments. Certain features that are described in thisspecification in the context of separate embodiments can also beimplemented in combination in a single embodiment. Conversely, variousfeatures that are described in the context of a single embodiment canalso be implemented in multiple embodiments separately or in anysuitable sub-combination. Moreover, although features may be describedabove as acting in certain combinations and even initially claimed assuch, one or more features from a claimed combination can in some casesbe excised from the combination, and the claimed combination may bedirected to a sub-combination or a variation of a sub-combination.Similarly, while operations are depicted in the drawings in a particularorder, this should not be understood as requiring that such operationsbe performed in the particular order shown or in sequential order, orthat all illustrated operations be performed, to achieve desirableresults.

Although embodiments of various methods and devices are described hereinin detail with reference to certain versions, it should be appreciatedthat other versions, embodiments, methods of use, and combinationsthereof are also possible. Therefore the spirit and scope of theappended claims should not be limited to the description of theembodiments contained herein.

The invention claimed is:
 1. A micropuncture kit for direct access intoa lumen of a surgically exposed vessel using direct visual guidance, thekit comprising: a micropuncture access needle comprising a proximal hubcoupled to an elongate shaft defining an inner lumen and a visible depthindicator positioned on the elongate shaft a distance away from a distaltip of the elongate shaft, wherein the visible depth indicator of themicropuncture access needle provides an indication as to whether themicrocatheter, when inserted into the vessel, will penetrate a wallthickness of the vessel without contacting a back side of a vessel wallof the blood vessel; an access guidewire sized to be received throughthe inner lumen of the micropuncture access needle, the guidewirecomprising a distal tip and at least one visible depth indicatorpositioned on the access guidewire a distance away from the distal tipof the guidewire; and a microaccess cannula comprising an elongate bodydefining an inner lumen and a plurality of visible depth indicatorsformed on the elongate body, wherein each of the plurality of visibledepth indicators identifies a distance from a distal tip of the cannulato a respective depth indicator; wherein alignment of a first visibledepth indicator of the at least one visible depth indicator positionedon the access guidewire with a proximal edge of the cannula provides avisual indication to a user that the distal tip of the guidewire isaligned with the distal tip of the cannula; wherein alignment of asecond visible depth indicator of the at least one visible depthindicator positioned on the access guidewire with a proximal edge of thecannula provides a visual indication to a user that the distal tip ofthe guidewire is aligned with the distal tip of the micropuncture accessneedle; wherein alignment of a third visible depth indicator of the atleast one visible depth indicator positioned on the access guidewirewith a proximal edge of the cannula provides a visual indication to auser that the distal tip of the guidewire positioned distally of thedistal tip of the micropuncture access needle by a predetermineddistance indicated by the third visible depth indicator.
 2. The kit ofclaim 1, wherein the access guidewire comprises a distalmost flexiblesection including the distal tip of the guidewire, a transition sectionproximal to the distalmost flexible section, and a stiffer core sectionextending proximally from the transition section.
 3. The kit of claim 2,wherein the distalmost flexible section is between 1 cm and 2 cm, andthe transition section is between 2 cm and 3 cm.
 4. The kit of claim 2,wherein the transition section and the core section are configured tosupport the microaccess cannula inserted into the vessel.
 5. The kit ofclaim 1, wherein the guidewire is in a range of 0.014″ to 0.018″ outerdiameter and wherein the micropuncture needle is in a range from 21 G to24 G.
 6. The kit of claim 1, wherein the at least one visible depthindicator positioned on the access guidewire has a proximal edge, adistal edge and a width extending between the proximal edge and thedistal edge.
 7. The kit of claim 6, wherein the distance away from thedistal tip of the guidewire is measured from the distal tip to thedistal edge of the at least one visible depth indicator.
 8. The kit ofclaim 6, wherein inserting the access guidewire through the inner lumenof the elongate shaft until the distal edge is aligned with a back endof the proximal hub of the access needle extends the distal tip of theguidewire beyond the distal tip of the elongate shaft an extensionlength.
 9. The kit of claim 8, wherein advancing the access guidewirethrough the inner lumen of the elongate shaft until the proximal edge isaligned with the back end of the proximal hub of the access needleextends the distal tip of the guidewire beyond the distal tip of theelongate shaft the extension length plus the width of the at least onevisible depth indicator.
 10. The kit of claim 9, wherein the extensionlength is 3 cm and the width of the at least one visible depth indicatoris 2 cm.
 11. The kit of claim 1, wherein the visible depth indicator ofthe access needle is a chemical-etched marker, a laser-etched marker, ora pad printed marker.
 12. The kit of claim 1, wherein a first of theplurality of visible depth indicators on the cannula comprises one markand the first visible depth indicator is 10 mm away from the distal tipof the cannula.
 13. The kit of claim 12, wherein a second of theplurality of visible depth indicators on the cannula comprises two marksand the second visible depth indicator is 20 mm away from the distal tipof the cannula.
 14. The kit of claim 13, wherein a third of theplurality of visible depth indicators on the cannula comprises threemarks and the third visible depth indicator is 30 mm away from thedistal tip of the cannula.
 15. The kit of claim 14, wherein a fourth ofthe plurality of visible depth indicators on the cannula comprises fourmarks and the fourth visible depth indicator is 40 mm away from thedistal tip of the cannula.
 16. The kit of claim 15, wherein a fifth ofthe plurality of visible depth indicators on the cannula is 50 mm awayfrom the distal tip of the cannula and comprises a solid band having awidth that is greater than a width of one mark.
 17. The kit of claim 1,wherein the distance the visible depth indicator of the access needle isfrom the distal tip of the elongate shaft is between 3 mm and 7 mm. 18.The kit of claim 1, wherein the visible depth indicator of the accessneedle is a chemical-etched marker, a laser-etched marker, or a padprinted marker.